Add test to verify no typing imports are ever used

Author: schloerke

tests/posit/connect/test_internal_code.py

@@ -0,0 +1,20 @@
+from pathlib import Path
+
+import pytest
+
+here = Path(__file__).resolve().parent
+root_dir = here.parent.parent.parent
+
+tests_dir = root_dir / "tests"
+src_dir = root_dir / "src"
+integration_tests_dir = tests_dir / "integration" / "tests"
+
+
+@pytest.mark.parametrize("path", [tests_dir, src_dir, integration_tests_dir])
+def test_no_from_typing_imports(path: Path):
+    for python_file in path.rglob("*.py"):
+        file_txt = python_file.read_text()
+        if "\nfrom typing import" in file_txt:
+            raise ValueError(
+                f"Found `from typing import` in {python_file.relative_to(root_dir)}. Please replace the import with `typing_extensions`."
+            )